1. Related Applications
This application is related to:
a. Satellite Dish Antenna Support Split Rim--U.S. Pat. No. Des. 285,685, PA1 b. Satellite Dish Antenna Support Rim--U.S. Pat. No. Des. 285,792 and PA1 c. Satellite Dish Antenna Outer Rim--U.S. Pat. No. Des. 285,074.
2. Field of the Invention
This invention relates to the design and construction of a satellite dish antenna. More particularly, it relates to a satellite dish antenna having modular segments for easy manufacture and installation.
3. Discussion of the Prior Art
Over the past decade, the use of satellite dish antennas by the consuming public has increased substantially. Two general categories of dish antennas have been involved. The first category contains those dish antennas made of solid material, such as fiberglass, which is molded into a parabolic shape. These antennas generally have the high gain and signal reception, but are expensive to ship and have a high wind load when installed. The second category of dish antennas relates to those antennas having a screen-mesh material for the reflective surface. Such antennas are assembled in sections and, therefore, are less expensive to ship. They also exhibit low wind load characteristics but have overall lower gain and signal reception. The reason for the lower gain in such screen-mesh antennas is, in primary part, due to their approximation of the true parabolic shape such as through use of a number of linearally shaped segments.
Prior to making an application for the present invention, a patentability search was performed. The results of this search are as follows:
______________________________________ Inventor U.S. Pat. No. Issue Date ______________________________________ E. Gerhard 2,181,181 Nov. 28, 1939 S. E. Mautner 2,471,828 May 31, 1949 L. Lewin et al. 2,985,851 May 23, 1961 D. S. Kennedy 2,997,712 Aug. 22, 1961 R. E. Thomas 3,234,550 Feb. 8, 1966 E. Kelly 3,286,270 Nov. 15, 1966 A. C. Maier 3,406,404 Oct. 15, 1968 H. A. Payne 3,543,278 Nov. 24, 1970 Rushing et al. 3,635,547 Jan. 18, 1972 Quequen 3,725,946 Apr. 3, 1973 Taggart, Jr. 3,832,717 Aug. 27, 1974 Taggart 3,971,023 July 20, 1976 Toshio 4,169,688 Oct. 2, 1979 Vines 4,201,991 May 6, 1980 Vines 4,249,184 Feb. 3, 1981 Davis 4,257,207 Mar. 24, 1981 Taggart 4,268,835 May 19, 1981 Bannister 1,604,899 Dec., 1981 Sayovitz 4,314,253 Feb. 2, 1982 Palmer et al. 4,315,265 Feb. 9, 1982 Hibbard et al. 4,378,561 Mar. 29, 1983 ______________________________________
The 1983 patent to Hibbard (U.S. Pat. No. 4,378,561) relates to a parabolic reflector antenna formed by assembling identical pie-shaped sections of parabolically curved plastic. The sections are preferably glued together along the joints provided along the radial edges.
The patents issued to Taggart (U.S. Pat. Nos. 3,832,717; 3,971,023; and 4,268,835) all relate to parabolic reflectors comprised of generally triangular shaped pedals joined together in an edgewise overlapping relationship. In the '023 and '717 patents, an outer rim is provided around the dish antenna to provide outer support. In the '835 patent, a tubular outer segmented rigid rim is provided wherein the opposing ends slideably engage with the next segment. The edgewise overlapping pedals are bolted together by means of a plurality of holes.
The 1970 patent issued to Payne (U.S. Pat. No. 3,543,278) also relates to a sectional parabolic reflector wherein individual pedal sections are held together by a support molding 17 as shown in FIG. 3 which in turn is bolted to the edges of each section.
The two patents issued to Vines (U.S. Pat. Nos. 4,201,991 and 4,249,184) relate to a parabolic antenna kit comprised of a number of pre-stressed support arms (made from wood) which supports a plurality of screen reflector segments. A tensioning cable engages the outer ends of each support arm and provides sufficient tension, upon assembly, to stress the support arms into a parabolic shape. The parabolic screen is connected to the wood support arms by means of staples or twisted wires.
The patents issued to Sayovitz (U.S. Pat. No. 4,314,253), to Kelly (U.S. Pat. No. 3,286,270), to Maier (U.S. Pat. No. 3,406,404), and to Palmer (U.S. Pat. No. 4,315,265) all relate to collapsible dish antennas of various shapes and configurations. The antennas are assembled as a whole and can be shipped in a collapsed position and at the site can be selectively moved into the operative position.
The remaining patents uncovered in the search are of interest but are not as pertinent to the present invention as are the above patents.
From an analysis of these prior art patents, it is clear that a parabolic dish antenna exhibiting the greatest gain with the lowest cost to the consuming public would be one that incorporates the following features: one that exhibits low wind load characteristics, one that is segmented for ease in shipping, one that is designed to be easily manufactured, and one that can be assembled at the site with a minimum of labor.
Typical of commerically available satellite dish antennas exhibiting low wind load being advertised at the date of this application are the following which antennas may or may not serve as prior art references to this invention.
ECI--This is an eleven foot antenna made from all stainless steel hardware which utilizes eight interchangeable corrosion-free reflector panels each panel having a reflective screen. Each reflective panel contains four segments wherein each segment has a linear outer rim. This antenna has an advertised 42.0 DB gain and advertises that it can be assembled in less than one hour. It is manufactured by BR Satellite Communication, 216-11 Kingsbury Avenue, Bayside, NWY 11364.
PARACLIPSE--The paraclipse antenna utilizes a welded aluminum rib and ring truss system having concentric ring trusses to which heavy expanded aluminum mesh is fastened. The paraclipse antenna has eight triangular segments with linear outer edges with two internal concentric ring trusses provided for support. PARACLIPSE is manufactured by Paradigm Manufacturing Inc., 6911 E. Side Road, Redding, Calif. 96001.
AN-1200--This is a twelve foot antenna utilizing micro-grid "see through" expanded aluminum reflecting surfaces. The grid antenna has an advertised 42.3 DB alleged gain. The antenna has sixteen segments supported by rib trusses and four concentric ring trusses. The fifth outer ring truss is curved. Model AN-1200 is manufactured by Conifer Corporation, 1400 North Roosevelt, Burlington, Iowa. 52601.
XL10A--This is a three meter screen antenna having a number of parabolically shaped rib trusses and an outer rim formed of linear elements between each rib truss. It is manufactured by Microsat, Route 47, Washington Depot, Conn. 06794.
TRIANGLE--This is a tweleve foot mesh antenna with an advertised 76.99% efficiency rating. It utilizes a rib and concentric ring truss system having 24 rib trusses and three concentric ring trusses. The outer ring is linear between each rib and it is made by Triangle Engineering Company, P.O. Drawer 38271, Houston, Tex. 77238.
LINDSAY--Lindsay has eight and ten foot screen dishes constructed from a rib design having eighteen rib trusses broken down into six segments each containing three rib sections. The concentric rim around the antenna is curved. Lindsay Specialty Products Ltd., 50 Mary Street, West Lindsay, Ontario, Canada K9B 4F7.
STARDISH II--This is an aluminum mesh satellite dish antenna having a pattern of concentric ring trusses and rib trusses and is made by Pilant Systems, 3532 Giande Blvd., Sacramento, Calif. 95832.
The ultimate goal in designing a screen-mesh satellite dish antenna is to provide a reflecting surface that is as near the shape of a true parabola as is possible. The present invention unlike the above screen-section approaches has each screen mesh section and each support rib stretch-formed into a parabolic shape. The present invention further eliminates the need for hundreds of bolts, washers, screws, or other fasteners which causes distortion to the reflecting surface and, therefore, lowers the overall efficiency of the antenna. Under the teachings of the present invention and unlike that set forth above, a unique rib-locking system is provided which holds each screen-mesh segment at a point below the upper reflecting surface of each support rib. Hence, the upper reflecting surface of each rib and the upper surface of each screen-mesh petal are all held in the same parabolic reflecting plane without causing distortion to the reflected signal. Because the ends of each screen-mesh petal are locked along the entire length of the support ribs, no stress is provided to the petals and each petal maintains its parabolic shape even in severe environmental conditions such as wind, ice, and snow. Finally, because of the simplicity of the design, the dish antenna of the present invention can be easily and rapidly assembled at a site.